JP2021011409A - Optical glass, optical element, optical system, interchangeable lense and optical device - Google Patents

Abstract

To provide an optical glass that has high refractive index, low dispersion, and low specific gravity.SOLUTION: Provided is an optical glass that has a glass composition of, in mass%, SiO2 component: 7.5 to 10.5%, B2O3 component: 13.5 to 16.5%, La2O3 component: 38 to 50%, Gd2O3 component: 6.3 over to 7.5%, Y2O3 component: 6 to 13%, Nb2O5 component: 6.5 to 8.5%, BaO component: 0 over to 2.5%, ZrO2 component: 4.5 to 7.5%.SELECTED DRAWING: None

Description

The present invention relates to optical glass, optical elements, optical systems, interchangeable lenses and optical devices.

In recent years, imaging devices and the like equipped with an image sensor having a high number of pixels have been developed, and high resolution is required for the optical system used for these. Patent Document 1 discloses an example of an optical glass that can be used in such an optical system.

Japanese Unexamined Patent Publication No. 2014-210695

The first aspect of the present invention is mass%, SiO ₂ component: 7.5 to 10.5%, B ₂ O ₃ component: 13.5 to 16.5%, La ₂ O ₃ component: 38 to 50. %, Gd ₂ O ₃ component: over 6.3% to 7.5%, Y ₂ O ₃ component: 6 to 13%, Nb ₂ O ₅ component: 6.5 to 8.5%, BaO component: over 0 ~ It is an optical glass having 2.5% and ZrO ₂ component: 4.5 to 7.5%.

The second aspect of the present invention is an optical element using the above-mentioned optical glass.

A third aspect of the present invention is an optical system including the above-mentioned optical element.

A fourth aspect of the present invention is an interchangeable lens including the above-mentioned optical system.

A fifth aspect of the present invention is an optical device including the above-mentioned optical system.

FIG. 1 is a perspective view of an image pickup apparatus including an optical element using optical glass according to the present embodiment. FIG. 2 is a front view of another example of an image pickup apparatus including an optical element using optical glass according to the present embodiment. FIG. 3 is a rear view of the image pickup apparatus of FIG. FIG. 4 is a block diagram showing an example of the configuration of a multiphoton microscope including an optical element using the optical glass according to the present embodiment.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

Unless otherwise specified in the present specification, the content of each component shall be mass% of the total mass of glass in the oxide conversion composition. The oxide-equivalent composition referred to here is based on the assumption that the oxides, composite salts, etc. used as raw materials for the glass constituents of the present invention are all decomposed into oxides at the time of melting, and the total mass of the oxides is used. It is a composition which describes each component contained in a glass as 100% by mass.

Further, in the present specification, "substantially not contained" means that the component is not contained as a component affecting the characteristics of the glass composition in excess of the concentration unavoidably contained as an impurity. means. For example, it is assumed that contamination of about 100 ppm or less in the manufacturing process is substantially not contained.

The optical glass according to the present embodiment has a SiO ₂ component: 7.5 to 10.5%, a B ₂ O ₃ component: 13.5 to 16.5%, and a La ₂ O ₃ component: 38 to 50 in mass%. %, Gd ₂ O ₃ component: over 6.3% to 7.5%, Y ₂ O ₃ component: 6 to 13%, Nb ₂ O ₅ component: 6.5 to 8.5%, BaO component: over 0 ~ It is an optical glass having 2.5% and ZrO ₂ component: 4.5 to 7.5%.

As the optical glass used in the optical system, one having a high refractive index and low dispersion is desired. In addition, there is an increasing demand for weight reduction of optical systems. With conventional optical glass, even if high refractive index and low dispersion can be achieved at a certain level, the specific gravity tends to increase, and there is a problem that such a demand cannot be met. In this regard, the optical glass according to the present embodiment can realize a low specific gravity that could not be achieved in the past, while having a high refractive index and low dispersion. Further, the optical glass according to the present embodiment also contributes to low cost. The low cost mentioned here is due to the fact that excellent physical properties can be exhibited without using a material with a high raw material cost as described later, and that the manufacturing cost of various products can be reduced by using an optical glass having a low specific gravity. Achieved. That is, the optical glass according to the present embodiment can achieve a low specific gravity while having a high refractive index and low dispersion without containing a large amount of expensive raw materials.

Conventionally, in order to obtain optical glass having a high refractive index and low dispersion, there has been a tendency to increase the ratio of rare earth components such as La ₂ O ₃ , Gd ₂ O ₃ , and Y ₂ O _{3 in} order to increase the refractive index. It was. However, the present inventors have, surprisingly, by controlling the ratio of such Y ₂ O ₃ in a predetermined ratio, a high refractive index, while a low dispersion, low specific gravity of the degree was not in the prior art can be achieved I got the finding. Then, as a result of diligent research based on such findings, the present inventors have completed the optical glass according to the present embodiment.

Hereinafter, the composition of the optical glass according to the present embodiment will be described.

SiO ₂ is a component that forms a glass skeleton, lowers the liquidus temperature (Tl), and improves chemical durability. If the content of SiO ₂ is too small, devitrification tends to occur easily. If the content of SiO ₂ is too large, the refractive index tends to decrease. From this point of view, the content of SiO ₂ is 7.5 to 10.5%. This upper limit is preferably 10%, more preferably 9.5%. This lower limit is preferably 8%, more preferably 8.5%. Within such a range, it is possible to increase the devitrification resistance and improve the moldability while increasing the refractive index.

B ₂ O ₃ is a component that forms a glass skeleton, lowers the liquidus temperature (Tl), and improves chemical durability. If the content of B ₂ O ₃ is too small, the meltability tends to deteriorate and devitrification tends to occur. If the content of B ₂ O ₃ is too large, the refractive index tends to decrease. In addition, the viscosity at the time of melting tends to decrease, making molding difficult. From this point of view, the content of B ₂ O ₃ is 13.5-16.5%. This upper limit is preferably 16%, more preferably 15.5%. This lower limit is preferably 14%, more preferably 14.5%. Within such a range, it is possible to increase the devitrification resistance and improve the moldability while increasing the refractive index.

La ₂ O ₃ is a component that increases the refractive index and decreases the dispersion (increases the Abbe number (ν _d )). If the content of La ₂ O ₃ is too small, the refractive index will decrease. If the content of La ₂ O ₃ is too large, the glass becomes unstable, the meltability decreases, and devitrification is likely to occur. From this point of view, the content of La ₂ O ₃ is 38 to 50%. This upper limit is preferably 48%, more preferably 47%. This lower limit is preferably 40%, more preferably 41%. Within such a range, high refractive index and low dispersion can be realized without lowering the devitrification resistance.

Gd ₂ O ₃ is a component that increases the refractive index and decreases the dispersion (increases the Abbe number (ν _d )). If the content of Gd ₂ O ₃ is too small, the refractive index will decrease. If the content of Gd ₂ O ₃ is too large, the glass becomes unstable, the meltability decreases, and devitrification is likely to occur. From this point of view, the content of Gd ₂ O ₃ is more than 6.3 to 7.5%. This upper limit is preferably 7%, more preferably 6.9%. This lower limit is preferably 6.35%, more preferably 6.4%. Within such a range, high refractive index and low dispersion can be realized without lowering the devitrification resistance.

Y ₂ O ₃ is a component that increases the refractive index and lowers the dispersion (increases the Abbe number (ν _d )), and is also a component that lowers the specific gravity. If the content of Y ₂ O ₃ is too small, the specific gravity tends to increase. If the content of Y ₂ O ₃ is too large, the glass becomes unstable, the meltability decreases, and devitrification is likely to occur. From this point of view, the content of Y ₂ O ₃ is 6 to 13%. This upper limit is preferably 12%, more preferably 11.5%. This lower limit is preferably 7%, more preferably 8%. Within such a range, high refractive index, low dispersion, and low specific gravity can be realized without lowering the devitrification resistance.

Nb ₂ O ₅ is a component having an effect of increasing the refractive index and increasing the dispersion (decreasing the Abbe number (ν _d )). If the content of Nb ₂ O ₅ is too small, it becomes difficult to increase the refractive index. If the content of Nb ₂ O ₅ is too large, the meltability is lowered and the liquidus temperature (Tl) is raised, which requires treatment at a high temperature and is highly dispersed. The content of Nb ₂ O ₅ is 6.5-8.5%. This upper limit is preferably 8%. This lower limit is preferably 7%, more preferably 7.5%. By setting it in such a range, it is possible to realize a high refractive index without high dispersion.

BaO is a component that increases the refractive index and decreases the dispersion (increases the Abbe number (ν _d )). If the BaO content is too small, the dispersion will be high. If the content of BaO is too large, it becomes difficult to increase the refractive index. From this point of view, the BaO content is more than 0 to 2.5%. This upper limit is preferably 2%, more preferably 1.5%. This lower limit is preferably 0.5%. With such a range, low dispersion is possible.

ZrO ₂ is a component having an effect of increasing the refractive index and increasing the dispersion. If the content of ZrO ₂ is too small, it becomes difficult to increase the refractive index. If the content of ZrO ₂ is too large, the dispersion becomes high, the meltability decreases, the liquidus temperature (Tl) rises, and treatment at a high temperature is also required. In addition, devitrification resistance tends to decrease, making vitrification difficult. From this point of view, the content of ZrO ₂ is 4.5 to 7.5%. This upper limit is preferably 7%, more preferably 6.5%. This lower limit is preferably 5%, more preferably 5.5%. By setting it in such a range, it is possible to realize a high refractive index without high dispersion.

In addition, the following preferred examples are further given for the combination and ratio of each component.

The optical glass according to the present embodiment may further contain one or more selected from the group consisting of WO ₃ , ZnO, MgO and Sb ₂ O ₃ . Among them, particularly preferable combinations include a combination of WO ₃ component: 0 to 5%, ZnO component: 0 to 5%, MgO component: 0 to 3%, and Sb ₂ O ₃ component: 0 to 1%. ..

WO ₃ has the effect of increasing the refractive index. The WO ₃ content is preferably 0-5%. This upper limit is more preferably 4% and even more preferably 3%. This lower limit is more preferably more than 0% and even more preferably 1%.

ZnO has the effect of increasing the refractive index of the optical glass and lowering the glass transition temperature. The ZnO content is preferably 0-5%. This upper limit is more preferably 4% and even more preferably 3%. This lower limit is more preferably more than 0%, still more preferably 0.5%.

MgO is useful for adjusting optical constant values. The content of MgO is preferably 0 to 3%. This upper limit is more preferably 2% and even more preferably 1.5%. This lower limit is more preferably more than 0%, still more preferably 0.5%.

Sb ₂ O ₃ promotes defoaming of optical glass. The content of Sb ₂ O ₃ is preferably 0 to 1%. This upper limit is more preferably 0.5%, still more preferably 0.3%. This lower limit is more preferably more than 0%, still more preferably 0.1%.

It is preferable that the optical glass according to the present embodiment substantially does not contain Ta ₂ O ₅ . When Ta ₂ O ₅ is contained, the raw material cost tends to increase. In this regard, the optical glass according to the present embodiment can be an optical glass having a high refractive index and low dispersion and a low specific gravity even if it does not substantially contain Ta ₂ O ₅ . It is also possible to reduce costs.

It is preferable that the optical glass according to the present embodiment does not substantially contain TiO ₂ . When TiO ₂ is contained, the transmittance tends to decrease. The optical glass according to the present embodiment can be an optical glass having a high refractive index, a low dispersion, and a low specific gravity even if it does not substantially contain TiO ₂ .

The ratio of Gd ₂ O ₃ to the total amount of La ₂ O ₃ and Gd ₂ O ₃ and Y ₂ O ₃ and Yb ₂ O ₃ (Gd ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ + Y ₂ O ₃ + Yb) ₂ O ₃ )) is preferably more than 0.05 to 0.12. The upper limit of this ratio is more preferably 0.11 and even more preferably 0.10. The lower limit of this ratio is more preferably 0.06. Within such a range, the devitrification resistance can be increased and the refractive index can be increased.

The ratio of SiO ₂ to _{B 2 O 3 (SiO 2 /} B 2 O 3) is preferably 0.60 to 0.80. The upper limit of this ratio is more preferably 0.70, still more preferably 0.68. The lower limit of this ratio is more preferably 0.62 and even more preferably 0.65. Within such a range, the viscosity of the glass can be increased and the moldability can be improved.

The ratio of Gd ₂ O ₃ and _Gd 2 _{O 3} to the total amount of the _{Y 2 O 3 (Gd 2 O} 3 / (Gd 2 O 3 + Y 2 O 3)) is preferably 0.50 or less. The upper limit of this ratio is more preferably 0.49. The lower limit of this ratio is more preferably 0.30, still more preferably 0.34. Within such a range, the specific gravity of glass can be effectively reduced.

Other components other than the above, such as known fining agents, colorants, defoaming agents, fluorine compounds, and phosphoric acid, for the purpose of clarifying, coloring, decoloring, and fine-tuning the optical constant value as necessary. Can be added in an appropriate amount to the glass composition as long as the effects of the present embodiment can be obtained. Further, not limited to the above components, other components may be added as long as the effects of the present embodiment can be obtained.

As each of the above-mentioned raw materials, it is preferable to use a high-purity product having a low content of impurities. For example, it is preferable to use a high-purity product for one or more of the SiO ₂ raw material, the B ₂ O ₃ raw material, and the La ₂ O ₃ raw material. A high-purity product contains 99.85% by mass or more of the component. As a result of reducing the amount of impurities by using a high-purity product, for example, the internal transmittance of light having a wavelength of 410 nm or less tends to be higher.

The method for producing the optical glass according to the present embodiment is not particularly limited, and a known method can be adopted. Further, as the manufacturing conditions, official conditions can be appropriately selected. As one of the preferable examples, one selected from oxides, hydroxides, phosphoric acid compounds (phosphates, orthophosphoric acid, etc.), sulfates, carbonates, nitrates, etc. corresponding to the above-mentioned raw materials is selected. Examples thereof include a step of selecting as a glass raw material, mixing the mixture, melting at a temperature of 1300 to 1400 ° C. to perform stirring and homogenizing, and then cooling and molding.

More specifically, raw materials such as oxides, hydroxides, sulfates, phosphoric acid compounds, carbonates and nitrates are prepared so as to have a target composition, preferably 1100 to 1400 ° C., more preferably 1100 to 1300 ° C. A manufacturing method can be adopted in which the mixture is melted at ° C. and stirred to make it uniform, the bubbles are cut off, and then the mixture is cast into a mold. The optical glass thus obtained can be reheat-pressed or the like to be processed into a desired shape and polished to obtain a desired optical glass or optical element.

Since the composition of the optical glass according to the present embodiment is easy to melt, it is easy to make the stirring uniform, and the production efficiency is excellent. That is, when 50 g of the raw material of the optical glass is heated at a temperature of 1300 to 1380 ° C., the time until the raw material melts is preferably less than 15 minutes, more preferably 13 minutes or less, still more preferably. It is less than 10 minutes. The "time until melting" here is the time from the start of heating and holding the raw materials required for the construction of the optical glass until these raw materials melt and cannot be visually confirmed near the liquid surface. Say.

Since the glass raw material melts in a short time as described above in the temperature range of 1300 to 1380 ° C., it is possible to prevent the remaining glass raw material from being mixed into the glass. Further, if the remaining glass raw material is forcibly melted and heated at a high temperature or held for a long time, it may cause a decrease in glass production efficiency and a deterioration in transmittance. However, according to the present embodiment. Such a problem does not occur.

Next, the physical characteristics of the optical glass according to the present embodiment will be described.

The optical glass according to the present embodiment, the range of refractive index _{(n d),} preferably 1.815 to 1.840. This upper limit is more preferably 1.835. This lower limit is more preferably 1.820. As described above, the optical glass according to the present embodiment can realize a high refractive index (a large refractive index ( _nd )) and a low dispersion (a large Abbe number (ν _d )). When optical glass having a high refractive index is used, for example, it is possible to design an optical element such as an optical lens to be thin.

The optical glass according to this embodiment has an Abbe number (ν _d ) in a range of preferably 41.0 to 43.5. This upper limit is more preferably 43.0. This lower limit is more preferably 42.0. In general, the higher the refractive index, the smaller the Abbe number (ν _d ) tends to be, and the optical glass according to the present embodiment has a low dispersion (large Abbe number (ν _d )) as an optical glass having a high refractive index. ).

In the optical glass according to the present embodiment, a suitable combination of a refractive index and Abbe number, refractive index _{(n d)} is 1.815 to 1.840, and the Abbe's number ([nu _d) is 41 It is 0 to 43.5. An optical glass having such a refractive index and an Abbe number can be suitably used as an optical glass having a high refractive index and low dispersion that can withstand practical use. For example, by combining such an optical glass with another optical glass, it is possible to design an optical system in which chromatic aberration and other aberrations are satisfactorily corrected.

The optical glass according to the present embodiment has a specific gravity (S _g ) of 4.72 or less, more preferably 4.71 or less. The optical glass according to the present embodiment can realize such a low specific gravity while having a high refractive index and a low dispersion. By using an optical glass having such a low specific gravity, it is possible to reduce the weight of the optical system and the manufacturing cost, for example.

The optical glass according to this embodiment is suitable as an optical element such as a lens provided in an optical device such as a camera or a microscope. Such optical elements include mirrors, lenses, prisms, filters and the like. Examples of the optical system including these optical elements include an objective lens, a condenser lens, an imaging lens, an interchangeable lens for a camera, and the like. Then, these can be used for an imaging device such as an interchangeable lens camera and a non-interchangeable lens camera, and a microscope such as a multiphoton microscope. The optical device is not limited to the above-mentioned imaging device and microscope, but also includes a video camera, a teleconverter, a telescope, binoculars, a monocular, a laser range finder, a projector, and the like. An example of these will be described below.

<Imaging device>
FIG. 1 is a perspective view of an image pickup apparatus including an optical element using optical glass according to the present embodiment.

The image pickup apparatus 1 is a so-called digital single-lens reflex camera (interchangeable lens camera), and the photographing lens 103 (optical system) is provided with an optical element using the optical glass according to the present embodiment as a base material. The lens barrel 102 is detachably attached to the lens mount (not shown) of the camera body 101. Then, the light that has passed through the lens 103 of the lens barrel 102 is imaged on the sensor chip (solid-state image sensor) 104 of the multi-chip module 106 arranged on the back side of the camera body 101. The sensor chip 104 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 106 is a COG (Chip On Glass) type module in which, for example, the sensor chip 104 is bare chip mounted on a glass substrate 105.

FIG. 2 is a front view of another example of an image pickup apparatus including an optical element using optical glass according to the present embodiment, and FIG. 3 is a rear view of the image pickup apparatus of FIG.

This image pickup device CAM is a so-called digital still camera (non-interchangeable lens camera), and the photographing lens WL (optical system) is provided with an optical element using the optical glass according to the present embodiment as a base material.

When the power button (not shown) is pressed, the shutter (not shown) of the photographing lens WL is released, and the light from the subject (object) is collected by the photographing lens WL and arranged on the image plane. An image is formed on the image pickup element. The subject image formed on the image sensor is displayed on the liquid crystal monitor LM arranged behind the image pickup device CAM. After deciding the composition of the subject image while looking at the liquid crystal monitor LM, the photographer presses the release button B1 to capture the subject image with the image sensor, and records and saves the subject image in a memory (not shown).

The image pickup device CAM is provided with an auxiliary light emitting unit EF that emits auxiliary light when the subject is dark, a function button B2 used for setting various conditions of the image pickup device CAM, and the like.

The optical system used in such a digital camera or the like is required to have higher resolution, lighter weight, and smaller size. In order to realize these, it is effective to use glass having a high refractive index for the optical system. In particular, there is a high demand for glass having a high refractive index but a lower specific gravity (Sg) and high press moldability. From this point of view, the optical glass according to the present embodiment is suitable as a member of such an optical device. The optical device applicable to this embodiment is not limited to the above-mentioned imaging device, and examples thereof include a projector and the like. The optical element is not limited to a lens, and examples thereof include a prism and the like.

<Multiphoton microscope>
FIG. 4 is a block diagram showing an example of the configuration of a multiphoton microscope 2 including an optical element using the optical glass according to the present embodiment.

The multiphoton microscope 2 includes an objective lens 206, a condenser lens 208, and an imaging lens 210. At least one of the objective lens 206, the condenser lens 208, and the imaging lens 210 is provided with an optical element using the optical glass according to the present embodiment as a base material. Hereinafter, the optical system of the multiphoton microscope 2 will be mainly described.

The pulse laser apparatus 201 emits ultrashort pulsed light having a near infrared wavelength (about 1000 nm) and a pulse width in femtosecond units (for example, 100 femtoseconds). The ultrashort pulsed light immediately after being emitted from the pulse laser device 201 is generally linearly polarized light polarized in a predetermined direction.

The pulse dividing device 202 divides the ultrashort pulsed light and emits the ultrashort pulsed light at a high repetition frequency.

The beam adjusting unit 203 has a function of adjusting the beam diameter of the ultrashort pulsed light incident from the pulse dividing device 202 according to the pupil diameter of the objective lens 206, and the wavelength and the ultrashort of the multiphoton excitation light emitted from the sample S. A function to adjust the focusing and divergence angle of ultrashort pulsed light to correct axial chromatic aberration (focus difference) with the wavelength of pulsed light, group while the pulse width of ultrashort pulsed light passes through the optical system It has a pre-churp function (group velocity dispersion compensation function) that gives the ultrashort pulsed light the opposite group velocity dispersion in order to correct the spread due to the velocity dispersion.

The repetition frequency of the ultrashort pulsed light emitted from the pulse laser device 201 is increased by the pulse dividing device 202, and the above-described adjustment is performed by the beam adjusting unit 203. Then, the ultrashort pulsed light emitted from the beam adjusting unit 203 is reflected by the dichroic mirror 204 in the direction of the dichroic mirror 205, passes through the dichroic mirror 205, is collected by the objective lens 206, and is irradiated to the sample S. .. At this time, by using a scanning means (not shown), the ultrashort pulsed light may be scanned on the observation surface of the sample S.

For example, when observing the sample S by fluorescence, the fluorescent dye in which the sample S is stained is multiphoton excited in the irradiated region of the ultra-short pulse light of the sample S and its vicinity, and the ultra-short wavelength is an infrared wavelength. Fluorescence (hereinafter referred to as "observation light") having a shorter wavelength than pulsed light is emitted.

The observation light emitted from the sample S in the direction of the objective lens 206 is collimated by the objective lens 206 and reflected by the dichroic mirror 205 or transmitted through the dichroic mirror 205 depending on the wavelength thereof.

The observation light reflected by the dichroic mirror 205 is incident on the fluorescence detection unit 207. The fluorescence detection unit 207 is composed of, for example, a barrier filter, a PMT (photomultiplier tube) or the like, receives observation light reflected by the dichroic mirror 205, and outputs an electric signal according to the amount of the light. .. Further, the fluorescence detection unit 207 detects the observation light over the observation surface of the sample S as the ultrashort pulse light is scanned on the observation surface of the sample S.

On the other hand, the observation light transmitted through the dichroic mirror 205 is descanned by scanning means (not shown), transmitted through the dichroic mirror 204, collected by the condenser lens 208, and placed at a position substantially conjugate with the focal position of the objective lens 206. It passes through the provided pinhole 209, passes through the imaging lens 210, and enters the fluorescence detection unit 211.

The fluorescence detection unit 211 is composed of, for example, a barrier filter, a PMT, or the like, receives the observation light imaged on the light receiving surface of the fluorescence detection unit 211 by the imaging lens 210, and outputs an electric signal according to the amount of the light. Further, the fluorescence detection unit 211 detects the observation light over the observation surface of the sample S as the ultrashort pulse light is scanned on the observation surface of the sample S.

By removing the dichroic mirror 205 from the optical path, the fluorescence detection unit 211 may detect all the observation light emitted from the sample S in the direction of the objective lens 206.

Further, the observation light emitted from the sample S in the direction opposite to that of the objective lens 206 is reflected by the dichroic mirror 212 and incident on the fluorescence detection unit 213. The fluorescence detection unit 213 is composed of, for example, a barrier filter, a PMT, or the like, receives the observation light reflected by the dichroic mirror 212, and outputs an electric signal according to the amount of the light. Further, the fluorescence detection unit 213 detects the observation light over the observation surface of the sample S as the ultrashort pulse light is scanned on the observation surface of the sample S.

The electric signals output from the fluorescence detection units 207, 211, and 213 are input to, for example, a computer (not shown), and the computer generates an observation image based on the input electric signals, and the generated observation. Images can be displayed and observation image data can be stored.

Next, Examples and Comparative Examples of the present invention will be described. Each table shows the composition of each component of the optical glass according to the examples and the comparative examples based on the mass% based on the oxide, and the evaluation results of the physical properties of the obtained optical glass. The present invention is not limited to these examples.

<Making optical glass>
The optical glass according to each Example and each Comparative Example was produced by the following procedure. First, glass raw materials such as oxides, hydroxides, phosphoric acid compounds (phosphate, orthophosphoric acid, etc.), carbonates, and nitrates were weighed so as to have the compositions (% by mass) shown in each table. Next, the weighed raw materials were mixed and put into a platinum crucible, melted at a temperature of 1300 to 1380 ° C., and stirred and homogenized. After the bubbles were cut off, each sample was obtained by lowering the temperature to an appropriate temperature, casting it into a mold or the like, slowly cooling it, and molding it.

<Measurement of optical glass>
-Refractive index ( _nd ) and Abbe number (ν _d )
The refractive index ( _nd ) and Abbe number (ν _d ) of each sample were measured and calculated using a refractive index measuring device (manufactured by Shimadzu Device Manufacturing Co., Ltd .: KPR-2000). The Abbe number (ν _d ) was calculated based on the following equation (1). The value of the refractive index was up to the sixth decimal place.

ν _d = (n _d -1) / (n _F −n _C ) ... (1)
n _d: refractive index n _F of the glass with respect to light having a wavelength of 587.562 nm: refractive index of the glass with respect to light having a wavelength of 486.133nm n _C: refractive index of the glass with respect to light having a wavelength of 656.273nm

・ Specific gravity (S _g )
The specific gravity (S _g ) of each sample was determined from the mass ratio of the same volume of pure water at 4 ° C.

-Melting time of the glass raw material The melting time of the glass raw material is the time from when 50 g of the glass raw material is well mixed and then placed in a platinum crucible and heat holding is started at a temperature of 1300 to 1380 ° C. until the glass raw material is melted. Means. In this example, it was determined that the glass raw material was melted because the undissolved residue of the glass raw material could not be visually confirmed on the glass liquid surface in the platinum crucible.

The results of each Example and each Comparative Example are shown in Tables 1 to 4. Unless otherwise specified, the content of the components in the table is based on mass%.

From the above, it was confirmed that each of the examples had a high refractive index, a low dispersion, and a low specific gravity. Furthermore, no devitrification was observed in any of the samples of each example. On the other hand, Comparative Example 1 had a high specific gravity of 4.74. Further, in Comparative Examples 2 and 3, various physical property values could not be measured because devitrification was observed in the sample.

1 ... Imaging device, 101 ... Camera body, 102 ... Lens barrel, 103 ... Lens, 104 ... Sensor chip, 105 ... Glass substrate, 106 ... Multi-chip module, 2 ... Multiphoton microscope, 201 ... Pulse laser device, 202 ... Pulse divider, 203 ... beam adjustment unit, 204,205,212 ... dichroic mirror, 206 ... objective lens, 207,211,213 ... fluorescence detection unit, 208 ... condenser lens, 209 ... pinhole, 210 ... imaging lens , S ... sample, CAM ... image pickup device, WL ... photographing lens, EF ... auxiliary light emitting unit, LM ... liquid crystal monitor, B1 ... release button, B2 ... function button

Claims (13)

By mass%
SiO ₂ component: 7.5 to 10.5%,
B ₂ O ₃ component: 13.5 to 16.5%,
La ₂ O ₃ component: 38-50%,
Gd ₂ O ₃ component: more than 6.3 to 7.5%,
Y ₂ O ₃ component: 6 to 13%,
Nb ₂ O ₅ component: 6.5-8.5%,
BaO component: over 0 to 2.5%,
ZrO ₂ component: 4.5-7.5%,
Optical glass. By mass%
WO ₃ component: 0-5%,
ZnO component: 0-5%,
MgO component: 0-3%,
Sb ₂ O ₃ component: 0 to 1%,
The optical glass according to claim 1. Substantially free of Ta ₂ O ₅ ,
The optical glass according to claim 1 or 2. Refractive index _{(n d)} is 1.815 to 1.840, and
The Abbe number (ν _d ) is 41.0 to 43.5.
The optical glass according to any one of claims 1 to 3. Specific gravity (S _g ) is 4.72 or less,
The optical glass according to any one of claims 1 to 4. When 50 g of the raw material is heated at a temperature of 1300 to 1380 ° C., the time until the raw material melts is less than 15 minutes.
The optical glass according to any one of claims 1 to 5. On a mass% basis,
The ratio of Gd ₂ O ₃ to the total amount of La ₂ O ₃ and Gd ₂ O ₃ and Y ₂ O ₃ and Yb ₂ O ₃ (Gd ₂ O ₃ / (La ₂ O ₃ + Gd ₂ O ₃ + Y ₂ O ₃ + Yb) ₂ O ₃ )) is more than 0.05 to 0.12,
The optical glass according to any one of claims 1 to 6. On a mass% basis,
The ratio of SiO ₂ to _{B 2 O 3 (SiO 2 /} B 2 O 3) is a 0.60 to 0.80,
The optical glass according to any one of claims 1 to 7. On a mass% basis,
The ratio of Gd ₂ O ₃ and _Y 2 _{O 3 Gd} to the total amount of the _{2 O 3 (Gd 2 O 3} / (Gd 2 O 3 + Y 2 O 3)) is 0.50 or less,
The optical glass according to any one of claims 1 to 8. An optical element using the optical glass according to any one of claims 1 to 9. An optical system including the optical element according to claim 10. An interchangeable lens comprising the optical system according to claim 11. An optical device comprising the optical system according to claim 11.

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